injection timing

[Jan Micka]

Hi guys,
I have purchased tach n time tool for adjusting the timing, hovever the gauge suplied with the kit for straightening the distance for magnetic probe hole is for 6.2 and my humvee happens to be 6,5. Does anybody have the gauge for the 6,5 that can take measurements?
The second question is the offset of the meter?
The third question is the timing value, is it 8 degrees before top dead center at 1400RPM? 1400 rpm seems to be quite low for normal operating rpms.
I do own F250 6,9 diesel and the timing there is set at 8 degrees BTDC at 2000 rpm which makes more sense as it is somewhere around these rpms the engine operates.
Could anybody give me more ifo, as I am located in Europe.
Thank you very much, nice rest of the day.
Jan

 

[Jan Micka]

When I tried to line up the marks, the truck has less power and rattles upon cold start like crazy. It was lined like that from the rebuilt, I have retarded the timing after I got it. After running through several tanks the IP started working properly as I think the advance piston was stuck. Suddenly it had retarded timing so I had to advance it. A week ago I tried to align it as it was from the rebuilt and it seems I lost some power plus the awfull rattle when cold. As I have the timing meter I would like to dynamicaly time it as the engineers intended.
Thanks for any input of the more knowledgeable guys.
Jan

 

[Mogman]

In what TM did you find those instructions?

 

[Jan Micka]

In what TM did you find those instructions?

Ops, it says 4 degrees at 1400rpm I believe, but I have never find the info about the 6,5. Not very good in searching on the internet, pardon me.

 

[Jan Micka]

Timing must be 3° ±2° after top dead center at 1300–1400 RPM. says the manual for the 6,2, is it the same for the 6,5. My main problem is the gauge for the 6,5 and not knowing the offset. I love my humvee and would like to run it as good s possible. Thanks.

 

[Barrman]

The 6.5 timing tab which looks to be at the 3 o’clock position on the timing cover needs a 30° offset for the timing tool. At least that is what I have found published. However, doing the math and comparing the 6.2 tab to the 6.5 tab. I think it should be 27° offset. Either value will get you close. Which really is all you can ask for on a used engine with unknown IP internal tolerances and timing chain wear.

The more heat and pressure diesel fuel is exposed to the quicker it ignites. That is why the idle timing is more negative than the 1400 rpm reading. The injection pump is also designed to retard the timing as rpms increase. 1400 rpm is when the IP is fully retarded.

-8° at idle and -4° at 1400 plus or minus 2° is what an AM General M998 manual says. That is the only reference I have ever found from a factory by the way.

Here are a pair of videos I did about this:

 

[Jan Micka]

I have played with the timing a little today. I have reatrded a little and the cold rattle is better. The funny part is when I play with the timing it also affects the shift point which should not to my belief. The TPS is attached to the throttle but anyway when I raise the timing I get shifts in higher rpm, that when I retard the timing. Might be that any change requires more throttle movement . The other thing I have found is when I floor it, it rews up and hesitates to shift to another gear, I have to let of the throttle. When driving like an old fart it shifts nicely and around 1500 rpm.